Nuclear Magnetic Resonance spectrometry is widely used in chemical studies for structure determination as well as presence, absence or concentration of a particular component in a sample. An NMR spectrum of a sample is generally determined by placing the sample in an elongate sample tube, placing the tube containing the sample in the field of a powerful magnet and selectively irradiating the sample with preselected radiofrequency signals and recording the effects of these signals on the sample. The sample tubes are formed from glass and are supplied in several sizes ranging from diameters of 1 mm to about 10 mm with lengths of about four inches to about seven inches long. The resolution of the spectrometer may be adversely affected by asymmetries in the sample tube and its placement within the magnetic field and irradiation coils. Accordingly, users of NMR spectrometers seek sample tubes and holders that minimize asymmetry.
In an effort to “average-out” sample asymmetry, some spectrometers axially spin samples on which the spectrum is being determined. More recently, NMR spectrometers have the capability to average-out some sample asymmetry electronically without spinning, but sample placement and positioning in the sample chamber is still important to optimize the resolution of the spectrometer. These more recent NMR spectrometers also utilize the tube closure to suspend the sample axially in the sample chamber. Thus, tube closures or caps need to do more than just close the tube. When the samples are not spun, the coaxiality of the outer diameter, the closure and the inside diameter of the tube, if not consistent and precise, may adversely effect the quality of the spectrum obtained.
In many cases, the materials whose NMR spectrum is being determined are derived from expensive and difficult to repeat studies. Accordingly, if a sample is lost or degraded because of a malfunction of the sample closure or the tube, the user may experience a substantial and expensive delay in their study. Thus, although there are many types of NMR sample systems and tube closure devices available, there is still a need for an NMR sample system and closure which is reliable, simple to use and allows the user of an NMR spectrometer to fully utilize the resolution capability of the spectrometer. If such a device also was compatible with available automated sample handling equipment, a further benefit to the art of NMR spectrum determination would be realized. Such a system and closure is disclosed herein.